1. Field of the Invention
The present invention relates to a light quantity adjusting apparatus such as a shutter apparatus or diaphragm apparatus mounted in an image-pickup apparatus such as a digital camera, and an improvement of an image-pickup apparatus provided with the light quantity adjusting apparatus.
2. Description of the Related Art
A camera which uses an image-pickup element has a narrow dynamic range and is therefore required to have a high shutter speed for adjusting the light quantity for a high degree of brightness.
However, problems caused by increasing the shutter speed include deterioration of light-shield blades. One of conventionally known methods for solving this problem is a method of increasing the thickness of the light-shield blades.
However, the light-shield blades are structured by punching out a sheet member made of polyester, etc., created into a uniform thickness, and therefore the thickness of the light-shield blades as a whole increases. As a result, the weight of portions unnecessary for reinforcement also increases, which is disadvantageous in increasing the shutter speed.
The same problem occurs with a diaphragm apparatus whose aperture diameter is changed by opening/closing the light-shield blades when the driving speed of the light-shield blades is increased.